Don't enforce X-Frame-Options for downloads.

content/browser/frame_host/ancestor_throttle.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/ancestor_throttle.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ skipping 87 matching lines @@
 
 AncestorThrottle::~AncestorThrottle() {}
 
 NavigationThrottle::ThrottleCheckResult
 AncestorThrottle::WillProcessResponse() {
   DCHECK(!navigation_handle()->IsInMainFrame());
 
   NavigationHandleImpl* handle =
       static_cast<NavigationHandleImpl*>(navigation_handle());
 
+  // Downloads should be exempt from checking for X-Frame-Options, so
+  // proceed if this is a download.
+  if (handle->is_download())
+    return NavigationThrottle::PROCEED;
+
   std::string header_value;
   HeaderDisposition disposition =
       ParseHeader(handle->GetResponseHeaders(), &header_value);
 
   switch (disposition) {
     case HeaderDisposition::CONFLICT:
       ParseError(header_value, disposition);
       RecordXFrameOptionsUsage(CONFLICT);
       return NavigationThrottle::BLOCK_RESPONSE;
 
@@ skipping 187 matching lines @@
       HeadersContainFrameAncestorsCSP(headers)) {
     // TODO(mkwst): 'frame-ancestors' is currently handled in Blink. We should
     // handle it here instead. Until then, don't block the request, and let
     // Blink handle it. https://crbug.com/555418
     return HeaderDisposition::BYPASS;
   }
   return result;
 }
 
 }  // namespace content